JP2004260948A - Power supply device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the size and weight of the entire power supply device by reducing the volume and weight of a lead storage battery. <P>SOLUTION: The power supply device comprises a main power supply part 10 that supplies power to an auxiliary unit 31 at normal time, and an auxiliary power supply part 20 that supplies power to the auxiliary unit 31 in an emergency. A battery (lead storage battery) 22 of the auxiliary power supply part 20 has a 7-cell constitution which is one more than a 6-cell constitution of a battery (lead storage battery) 12 of the main power supply part 10. The auxiliary power supply part 20 of the power supply device has a setting of the voltage, which is supplied from the battery 22 of the auxiliary power supply part 20, being higher than that supplied from the battery 12 of the main power supply part 10 while equal to or lower than the upper limit voltage of a continuous rating of he auxiliary unit 31. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device for supplying power to an auxiliary machine from an auxiliary power supply section in place of a main power supply section in the event of an emergency such as an abnormality in a main power supply section, and guaranteeing the operation of the auxiliary machine.
[0002]
[Prior art]
In recent years, with the enforcement of the PL Law (Product Liability Law), efforts for safe operation of vehicles and creation of standards have been emphasized. Conventionally, as an example of this safety measure, an emergency notification device called a May Day system has been introduced. In this device, when a power generation system of a vehicle, a storage battery, a power line, and the like lose power supply capability due to damage or the like. In some cases, an auxiliary power supply for ensuring the operation of the emergency notification device is employed instead of the main power supply.
[0003]
In addition, in order to ensure the safe operation of vehicles, an electronic control system using a technology called by-wire technology will be used to control the running system such as engine, brake, steering, etc. A technology for avoiding an accident by supplying power from an auxiliary power supply unit is becoming important.
[0004]
Examples of the power supply used for the auxiliary power supply unit include a storage battery and a capacitor. The storage battery is superior in terms of the cost ratio of the discharge performance. Further, among these power sources, lead storage batteries are the most excellent in discharge characteristics in an extremely low temperature state of −30 ° C. to −40 ° C. in consideration of external environmental conditions of the earth. For this reason, a lead storage battery has been used as an auxiliary power supply in the above-described emergency notification device. As such an auxiliary power supply device, for example, there is one as disclosed in Patent Document 1.
[0005]
[Patent Document 1]
JP-A-5-244704 (page 2-3, FIG. 1)
[0006]
[Problems to be solved by the invention]
However, the lead storage battery has inferior discharge performance per volume or weight as compared with other storage batteries and capacitors, and in order to increase the discharge performance, the size and weight of the lead storage battery must be increased. Become. That is, for example, the power supply voltage of a vehicle used with a 12V battery is specified in the range shown in FIG. 7, and in a region of 10V or less, the operation of the accessory system is not guaranteed due to insufficient voltage, and In the region of 16 V or more, the withstand voltage of the accessory parts is exceeded. Therefore, the power supply voltage of the vehicle is set to an appropriate allowable range in the range of 10 V to 16 V.
[0007]
FIG. 8 schematically shows the output voltage characteristics of a general 12V lead-acid battery (six-cell configuration) used in this vehicle, and the current required for the operation of the accessories is as shown in FIG. The value is selected such that a voltage of 10 V or more is guaranteed for the required time. In this figure, when a normal discharge is applied, the voltage of the 12V battery instantaneously rises to the maximum voltage of about 13.2V, and thereafter the voltage gradually decreases. This phenomenon occurs when the current flowing during discharge is small or the dash-dot line A has a large capacity of the storage battery, and this voltage is high, and when the current flowing during discharge is large or the dash-dot line B has a small capacity of the storage battery. This voltage will be lower.
[0008]
Therefore, there is still room for the auxiliary machine withstand voltage upper limit value 16V shown in FIG. However, in the case of the one-dot chain line B in FIG. 8, the lower limit value of the auxiliary equipment operation guarantee of 10 V may be lower than the lower limit, and the operation limit of the auxiliary equipment may not be reached. For this reason, when the current is fixed, it is necessary to increase the capacity of the storage battery and increase the voltage of the battery, and as a result, the power supply device becomes large and the weight thereof increases, and the vehicle However, there is a problem that the installation space and weight are affected.
[0009]
The present invention has been made in view of the above problems, and has as its object to provide a power supply device capable of reducing the volume and weight of a storage battery and reducing the size and weight of the entire device.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, in the power supply device according to claim 1, a power supply device having a main power supply unit that supplies power to an auxiliary device and operates the auxiliary device, wherein the power supply device has a voltage higher than a voltage of the main power supply unit. And an auxiliary power supply unit that supplies a voltage that is equal to or less than an upper limit voltage of the continuous rating of the auxiliary device, and a switching unit that switches a voltage supplied from the main power supply unit and the auxiliary power supply unit and supplies the voltage to the auxiliary device. There is provided a power supply device characterized by comprising:
[0011]
According to the first aspect of the present invention, the voltage supplied from the auxiliary power supply is set to be higher than the voltage of the main power supply (for example, 13.2 V) and equal to or less than the upper limit voltage (for example, 16 V) of the auxiliary equipment. By doing so, the volume and weight of the storage battery are reduced.
[0012]
Further, in the power supply device according to claim 2, the auxiliary power supply unit has a storage battery of a predetermined number of cells and the storage battery is higher than the voltage of the main power supply unit and equal to or lower than the upper limit voltage of the continuous rating of the auxiliary machine. Charging means for charging to a voltage.
[0013]
According to the second aspect of the present invention, when the storage battery charging means (charging circuit) is provided, the storage battery of the auxiliary power supply unit is charged at a voltage within the range set in the first aspect, thereby charging the battery. The current is reduced, and the size and cost of the charging circuit are reduced.
[0014]
Also, in the power supply device according to claim 3, the auxiliary power supply unit further includes a detection unit that measures an internal resistance value of the storage battery and detects a deterioration state of the storage battery based on the measurement result. Features.
[0015]
According to the third aspect of the present invention, for example, the internal resistance of the battery which has been increased by increasing the number of cells is obtained, and the deterioration state of the battery is accurately detected based on the internal resistance.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
A preferred embodiment of a power supply device according to the present invention will be described with reference to the accompanying drawings in FIGS.
[0017]
(Embodiment 1)
FIG. 1 is a configuration diagram illustrating an example of a configuration of a power supply device according to the present invention. In the figure, a main power supply unit 10 includes a generator 11, a battery 12, and fuses 13 to 15, and power lines 16 and 17 from the generator 11 and the battery 12 are connected to a main power line 18 via fuses 13 and 14. The main power supply line 18 is connected to an auxiliary device 31 via a power supply switching circuit 30. Therefore, at normal times, power is supplied from the generator 11 and the battery 12 to the auxiliary machine 31 via the main power supply line 18.
[0018]
The auxiliary power supply unit 20 includes a charging circuit 21 and an auxiliary battery 22. The charging circuit 21 is connected to the battery 12 via a power supply line 19, and charges the auxiliary battery 22 with power supplied from the battery 12 in a normal state. It is carried out. The battery 22 is connected to the auxiliary device 31 via the power supply switching circuit 30. In an emergency such as an abnormality of the main power supply unit 10, the power supply switching circuit 30 is switched, and power is supplied from the battery 22 to the auxiliary device 31. Each of the batteries 12 and 22 of the main power supply unit 10 and the auxiliary power supply unit 20 is composed of, for example, a lead storage battery. A typical 12 V lead storage battery of the main power supply unit 10 used in a vehicle has a 6-cell configuration. It has become.
[0019]
The inventors of the present invention have performed the following verification on the power supply device having such a configuration. That is, as shown in FIG. 2, in a lead storage battery, the battery capacity at which the minimum voltage for 10 seconds was 10 V or more during a discharge of 25 A was determined in relation to the number of cells. As a result, the capacity rapidly decreases from 50 Ah to 3.6 Ah between 5 cells and 6 cells, but from 6 cells, 7 cells are 1.9 Ah, 8 cells are 1.3 Ah, and 9 cells are 1.1 Ah. It turns out that it decreases gradually.
[0020]
Further, based on this relationship, the volume ratio when each cell configuration satisfies the required performance is shown in FIG. 3, and the weight ratio is shown in FIG. Here, the volume ratio is 100% for 6 cells, about 67% for 7 cells, about 55% for 8 cells, and 9 cells or more from 8 cells. It was gradually decreasing. The weight ratio is 100% for 6 cells, about 55% for 7 cells, about 38% for 8 cells, and more than 9 cells gradually decreases from 8 cells Was.
[0021]
From these relations, it was found that when the lead storage battery had a 7-cell configuration compared to a 6-cell configuration, the volume ratio was greatly improved to about 2/3 and the weight ratio was significantly improved to about 1/2. Further, in the case of an 8-cell or 9-cell configuration, further improvement is achieved, but the improvement rate becomes smaller.
[0022]
FIG. 5 shows the output voltage range in each cell configuration. As is clear from FIG. 5, the output voltage range of the 8-cell configuration or more exceeds the existing auxiliary equipment withstand voltage upper limit of 16 V. Not only will a complete redesign of the system be required, but this will also lead to higher costs due to increased component ratings, and as a result, the overall cost of the vehicle will be more expensive than a typical 6-cell lead-acid battery. I knew it would be.
[0023]
Therefore, in this embodiment, considering the above-described detection results, the battery (lead storage battery) 22 of the auxiliary power supply unit 20 has a seven-cell configuration that is one more than the six-cell configuration of the battery 12 of the main power supply unit 10. I do. Further, in this embodiment, the voltage supplied from battery 22 is higher than the voltage supplied from battery 12 of main power supply unit 10 (for example, the maximum voltage 13.2 V in the case of a 6-cell configuration), and It is set to be equal to or lower than the upper limit voltage of the continuous rating (for example, the auxiliary machine withstand voltage upper limit value of 16 V).
[0024]
As described above, in this embodiment, the storage battery for the auxiliary power supply has a seven-cell configuration that is one more than the number of cells of the storage battery for the main power supply, and the voltage supplied from the storage battery for the auxiliary power supply is the main power supply unit. 3 and 4, the volume and weight of the storage battery can be reduced as shown in FIG. 3 and FIG. Can be reduced in size and weight.
[0025]
In addition, in the auxiliary power supply unit 20 according to this embodiment, the charging circuit 21 of the battery 22 causes the voltage supplied from the battery 22 to be lower than the voltage supplied from the battery 12 of the main power supply unit 10 in accordance with this setting. The battery 22 of the auxiliary power supply unit 20 is charged so as to be large and equal to or smaller than the auxiliary machine withstand voltage upper limit value.
[0026]
Here, if the vehicle is left at an average temperature of 40 ° C. for one month in the case of a single cell capacity value for guaranteeing an output voltage of 10 V at each cell number shown in FIG. 10%. The time t required to charge the battery until it is fully charged by a constant current charger having 1 A as the upper limit of the charging current is 5 Ah in the case of 5 cells, the self-discharge amount is 50 Ah × 10% = 5 Ah. Assuming that the efficiency is 90%, t = 5Ah / (1A / 90%) = 5.6 hours.
[0027]
Similarly, in the case of 6 cells, the self-discharge amount 10% is 3.6 Ah × 10% = 0.36 Ah, and the time t to full charge t = 0.36 Ah / (1 A / 90%) = 0.4. In the case of 7 cells, the self-discharge amount of 10% is 1.9 Ah × 10% = 0.19 Ah, and the time t to full charge is t = 0.19 Ah / (1A / 90%) = 0.21 hours. , 8 cells, the self-discharge amount of 10% is 1.3 Ah × 10% = 0.13 Ah, the time t to full charge t = 0.13 Ah / (1A / 90%) = 0.14 hours, In the case of 9 cells, 1.1Ah × 10% = 0.11Ah, and the time t to full charge is t = 0.11Ah / (1A / 90%) = 0.12 hours.
[0028]
However, when charging is performed at 1 A with 7 cells, the capacity ratio becomes 0.53 C. Usually, the upper limit of the charging current is generally limited to 0.2 to 0.3 C in order to prevent deterioration of the battery. Here, assuming that the capacity ratio is 0.3 C as the upper limit, 1.9 Ah × 0.3 C = 0.57 A in 7 cells, 0.33 hours, and similarly, 0.38 hours in 8 cells and 9 cells. The charging time does not change.
[0029]
As described above, in this embodiment, the storage battery for the auxiliary power supply has a seven-cell configuration, and the voltage supplied from the storage battery for the auxiliary power supply is higher than the voltage supplied from the storage battery in the main power supply unit. Since the battery is charged so as to be equal to or lower than the withstand voltage upper limit value, the charging time is shortened, and the battery can be charged even during a short running time of the vehicle. Replenishment can be performed quickly, and emergency power can always be secured.
[0030]
Further, in this embodiment, the self-discharge amount and the battery capacity are in a proportional relationship, and if the capacity of the storage battery is reduced by increasing the number of cells, the charging current can be reduced, thereby reducing the size and cost of the charging circuit. be able to.
[0031]
In this embodiment, the case where the battery of the main power supply unit is a 12V battery is described. However, the present invention is not limited to this. For example, even when the battery of the main power supply unit is a 24V battery or a 36V battery, The auxiliary power supply is set under the same conditions as the condition that the voltage supplied from the storage battery for the auxiliary power supply is set to be higher than the voltage supplied from the storage battery of the main power supply unit and equal to or less than the auxiliary withstand voltage upper limit value. By configuring the battery of the unit, the same effect as in the first embodiment can be obtained.
[0032]
(Embodiment 2)
FIG. 6 is a configuration diagram showing another example of the configuration of the power supply device according to the present invention. In the drawing, the difference from the configuration of the first embodiment shown in FIG. 1 is that an auxiliary power supply unit 20 is provided with a battery state detection circuit 23 to detect the battery deterioration state of the battery 22.
[0033]
The battery state detection circuit 23 detects the deterioration state of the battery by measuring the impedance of the battery 22, which is a lead storage battery, for example, the internal resistance value of the battery. It is configured. Next, a method of measuring the internal resistance value of the battery by the battery state detection circuit 23 will be described.
[0034]
Here, the discharge current is I, the internal resistance value of the entire battery incorporated in the auxiliary power supply unit 20 is R (R6 is a 6-cell configuration, R7 is a 7-cell configuration), and the voltage change during constant current discharge is If ΔV, r is the internal resistance value of the unit cell, and Ah is the capacity of the unit cell (capacity of the built-in battery),
Internal resistance value R = ΔV / I (1)
More required. Here, if the minimum voltage for 10 seconds at the time of discharging at 25 A is guaranteed to be 10 V or more, the battery capacity is about 3.6 Ah in a 6-cell configuration, and the measured R is about 100 mΩ. If this is a seven-cell configuration, the battery capacity is 1.9 Ah, and the internal resistance value is almost inversely proportional to the capacity, so that R is approximately doubled.
[0035]
That is,
R6 = r6 × 6 (2)
r7 = r6 × 1.9 (3)
R7 = r7 × 7 (4)
From the equations (2) and (3), the internal resistance value r7 of the unit cell in the seven cells is
r7 = R6 × (1.9 / 6) (5)
Substituting equation (5) into equation (4) gives
R7 = R6 × (1.9 / 6) × 7 = R6 × 2.2
It becomes. As is apparent from the calculation results, for example, when the measurement is performed at the same discharge current value I, the voltage change ΔV at the time of constant current discharge in the case of 7 cells is obtained from the equation (1). 2.2 times the voltage change at the time.
[0036]
As described above, in this embodiment, the internal resistance value of the battery of the auxiliary power supply unit in the 7-cell configuration is 2.2 times the internal resistance value of the battery of the auxiliary power supply unit in the 6-cell configuration, and is proportional to this. Since the voltage change also becomes 2.2 times, it is hard to be affected by noise and the measurement accuracy is increased, and accordingly, it is possible to accurately detect the deterioration of the battery.
[0037]
Further, in this embodiment, when the voltage change to be measured is the same in the 6-cell configuration and the 7-cell configuration, the discharge current value I can be halved in the case of the 7-cell configuration. The circuit can be reduced in size and weight.
[0038]
The present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the present invention.
[0039]
【The invention's effect】
As described above, in the present invention, the voltage supplied from the auxiliary power supply is set to be higher than the voltage supplied from the main power supply and to be equal to or less than the upper limit voltage of the continuous rating of the auxiliary equipment. The weight can be reduced, and the entire device can be reduced in size and weight.
[0040]
According to the present invention, when a charging circuit for a storage battery is provided, the capacity of the storage battery is reduced by increasing the number of cells, and the storage battery of the auxiliary power supply unit is charged with a voltage within the range set in claim 1. As a result, the charging current is reduced, and the size and cost of the charging circuit can be reduced.
[0041]
In addition, in the present invention, the internal resistance of the battery increases due to the increase in the number of cells, and the voltage change increases in proportion to the increase. Therefore, the effect of noise is reduced and the measurement accuracy is increased. Deterioration can be accurately detected.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an example of a configuration of a power supply device according to the present invention.
FIG. 2 is a relationship diagram showing a single cell capacitance value for guaranteeing an output voltage of 10 V for each number of cells.
FIG. 3 is a relationship diagram showing a volume ratio according to each cell configuration.
FIG. 4 is a relationship diagram showing a weight ratio according to each cell configuration.
FIG. 5 is a relationship diagram showing an output voltage range in each cell configuration.
FIG. 6 is a configuration diagram showing another example of the configuration of the power supply device according to the present invention.
FIG. 7 is a diagram showing an appropriate range of a power supply voltage of a vehicle used with a 12V battery.
FIG. 8 is a diagram showing discharge voltage characteristics of a storage battery.
[Explanation of symbols]
Reference Signs List 10 Main power supply unit 11 Generators 12 and 22 Batteries 13 to 15 Fuse 16, 17, 19 Power supply line 18 Main power supply line 20 Auxiliary power supply unit 21 Charging circuit 23 Battery state detection circuit 30 Power supply switching circuit 31 Auxiliary device I Discharge current value R Internal resistance r Internal resistance t Time ΔV Voltage change

Claims (3)

In a power supply device having a main power supply unit for supplying power to the auxiliary machine and operating the auxiliary machine,
An auxiliary power supply unit that supplies a voltage that is greater than the voltage of the main power supply unit and is equal to or less than the upper limit voltage of the continuous rating of the auxiliary machine;
A switching unit that switches a voltage supplied from the main power supply unit and the auxiliary power supply unit, and supplies the voltage to the auxiliary device;
A power supply device comprising: The auxiliary power supply unit includes:
A storage battery of a predetermined number of cells;
Charging means for charging the storage battery to a voltage higher than the voltage of the main power supply unit and equal to or lower than the upper limit voltage of the continuous rating of the auxiliary machine,
The power supply device according to claim 1, further comprising: The auxiliary power supply unit includes:
The power supply device according to claim 2, further comprising a detecting unit that measures an internal resistance value of the storage battery and detects a deterioration state of the storage battery based on the measurement result.

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